ERBB2 and cancer: Gastro-oesophageal carcinoma (GOC) represents the third leading cause of cancer death worldwide,1 with a rising incidence of junctional cancers2 as well as tumours developing among younger individuals.3 In this tumour, the identification of new targets for effective treatment represents an unmet need.4 Up to now, the human epidermal growth factor receptor 2 (HER2) is the only available biomarker for personalised treatment in metastatic GOC.